A 61-year-old woman presented with an acute condition involving confusion, abdominal cramps and bloody diarrhea six hours after accidental ingestion of colocynth mistaken for zucchini. Colonoscopic examination revealed pseudomembranous colitis though the patient had no condition known to be associated with pseudomembranous colitis. Within ten days the mental state returned to normal and the colitis resolved completely. It is suggested that the colitis was caused by the ingestion of colocynth.